Adjustable fin system

ABSTRACT

An adjustable fin system for a watercraft such as a surfboard, includes a fin having a base, a foot extending from the base, a fin box mountable within a hull of the watercraft and a manually operable detent mechanism for releasably holding the fin in a plurality of different positions relative to the fin box. The fin box defines a cavity for receiving the foot. The cavity has an opening on a first surface through which the foot is inserted. The opening and the base are relatively dimensioned so that when the foot is received within the cavity the base substantially covers the opening.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Stage of International Application No.PCT/AU03/00517, filed May 2, 2003, which was published in English underPCT Article 21(2), which in turn claims the benefit of AustralianProvisional Application No. PS 2163, filed May 7, 2002. Bothapplications are incorporated herein in their entirety.

FIELD

The present invention relates to an adjustable fin system for awatercraft and in particular, though not exclusively, for a surfboard.

BACKGROUND

Many different types of adjustable fin systems are known particularly inrelation to surfboards. One such system is described in U.S. Pat. No.4,044,416 (Brewer et al) which discloses a fin holder set in theunderside of a surfboard defining an elongate channel for receiving thebase of a fin for lengthwise adjustment of the fin relative to thesurfboard. A clamp is provided which is slidable lengthwise in thechannel and is engagable with the fin for releasably retaining the finrelative to the surfboard.

A further system is described in U.S. Pat. No. 5,997,376 (Block et al)which discloses a fin mounting system for a surfboard including a boxwhich is embedded within a surfboard by producing a through cavitywithin the surfboard, placing the box within the through cavity and thenpouring a hardenable resin between the box and the cavity to fix thesame in the surfboard. A separate fin is then inserted into the box. Thefin is adjustable longitudinally and can be fixed into a number ofdifferent positions by way of a fastener comprising a conventional nutand bolt where the nut is embedded into the fin.

Another system is described in U.S. Pat. No. 5,215,488 (Bailey) whichteaches the insertion of a mounting box defining an elongated channelinto the hull of a watercraft and a fin adjustably mounted in themounting box. A locking device is provided for adjustably locking thefin at different positions along the channel. The locking deviceincludes a flat parallelogram shaped locking nut with a rotationalbiasing spring which are supported by the fin, with the nut receivablewithin an internal recessed lateral groove formed in the elongatedchannel.

Further fin mounting systems are described in U.S. Pat. No. 4,421,492(Leva) and U.S. Pat. No. 5,934,963 (Frizzell).

While all of the abovementioned fin mounting systems provide differentmeans for moving a fin longitudinally relative to the hull of awatercraft, they suffer from one or more of the following problems. Themounting boxes in many cases are provided with openings for receiving afin which are exposed to water flow, or are provided with clamps orother locking devices which are directly exposed to water flow thusadversely affecting the hydrodynamics of the associated water craft.Some of the systems also require the use of screws or nuts which requiretools such as screwdrivers or spanners in order to allow adjustment ofthe fin. These systems are particularly disadvantageous if it isrequired to change the position of the fin while in the water wheretypically, at least in the case of a surfboard, the user of the craftwould not be in possession of such tools. Further, systems which requirescrews, nuts and/or springs are often subject to rapid degradation byaction of water, and in particular salt water. Another problem is thatthe typical forces created in use of the fins act in a manner todisengage the fin in some of the prior at mounting systems.

SUMMARY

It is an object of the present invention to provide an adjustable finsystem for a watercraft which attempts to overcome at least one of theabovementioned problems in the known prior art.

According to the present invention there is provided an adjustable finsystem for a Watercraft having a hull, said system including at least:

-   a fin having a base;-   a foot coupled to said base;-   a fin box mountable in the hull of said water craft, said fin box    defining a cavity for receiving said foot, said cavity having an    opening on a first surface of said fin box through which said foot    is inserted, said opening and said base relatively dimensioned so    that when said foot is received in said cavity, said base    substantially covers said opening; and,-   a manually operable detent mechanism for releasably holding said fin    in a plurality of different positions relative to said fin box.

Preferably said detent mechanism includes a first engagement means onsaid foot; and a second engagement means in said fin box; said first andsecond engagement means mutually engagable in a plurality of differentpositions along a length of said cavity.

Preferably said detent mechanism includes:

-   a first pin resiliently supported on said foot; and,-   a channel formed in said fin box and extending at least in part, in    a direction of the length of said fin box;    wherein said first and second engagement means are mutually engaged    when said first pin is in said channel, and the position of the fin    is changeable relative to the fin box by resilient deflection of    said first pin relative to said foot and sliding of said first pin    along said channel.

Preferably said foot is provided with a second transversely extendingpin, wherein said second pin and said first engagement means arerespectively located near opposite ends of said foot and said first pinis intermediate of said second pin and said first engagement means.

Preferably said channel includes first and second portions for receivingsaid first and second pins respectively, wherein said first and secondportions are spaced from each other in a direction transverse to thelength of said fin box.

Preferably said fin box includes a feed channel connecting said firstand second portions and extending to said opening.

Preferably one of said first and second engagement means is in the formof an elongated rack and the other of said first and second engagementmeans is in the form of at least one tooth for engaging said rack.

Preferably said detent mechanism includes a resilient element whichsupports said first pin, said resilient element supported by said foot.

In one embodiment said resilient element is in the form of a body ofresilient material disposed in a recess formed in said foot.

In an alternate embodiment said detent mechanism includes a fingercoupled at one end to said foot.

Preferably said foot includes a first part attached to said base and asecond part extending from one side of said first part in a planecontaining said fin and spaced from said base.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the accompanying drawings in which:

FIG. 1 is a side view of one embodiment of the adjustable fin system;

FIG. 2 is a top view of the adjustable fin system depicted in FIG. 1;

FIG. 3 is a perspective view of a fin incorporated in the adjustable finsystem shown in FIGS. 1 and 2;

FIG. 4 is a side view of the fin depicted in FIG. 3 with a resilientelement and pin of the system removed;

FIG. 5 is an exploded perspective view of the resilient element and pinincorporated in the fin depicted in FIG. 3;

FIG. 6 is a plan view of one part of a mounting box incorporated in theadjustable fin system;

FIG. 7 is a perspective view of the part of the fin box depicted in FIG.6;

FIG. 8 is a plan view of a second part of the fin box incorporated inthe adjustable fin system;

FIG. 9 is a perspective view of the second part of the fin box depictedin FIG. 8;

FIG. 10 is a side view of a fin for a second embodiment of theadjustable fin system;

FIG. 11 is a perspective view of the fin depicted in FIG. 10; and,

FIG. 12 is an end view of the fin depicted in FIG. 10.

DETAILED DESCRIPTION

Referring to the accompanying drawings, and in particular FIGS. 1 and 2,it can be seen that an adjustable fin system 10 for a water craft suchas a surfboard (not shown) includes a fin 12 having a base 14, a fin box16 mountable within a hull of the surfboard, and a manually operabledetent mechanism 18 for releasably holding the fin 12 in a plurality ofdifferent positions relative to the fin box 16. The fin 12 includes afoot 20 which extends from the base 14 and is provided with firstengagement means in the form of teeth 22 on a lower surface 24 near oneend 26 of the foot 20. The fin box 16 defines a cavity 28 for receivingthe foot 20. The cavity 28 has an opening 30 (see FIG. 7) on a firstsurface 32 through which the foot 20 is inserted. The opening 30, andthe base 14 of the fin 12 are relatively dimensioned so that when thefoot 20 is received within the cavity 28 the base 14 substantiallycovers the opening 30.

The detent mechanism 18 includes a resilient element which in thepresent embodiment is in the form of a block or body 34, supported bythe foot 20, a first pin 36 supported by the resilient element 34 (seein particular FIGS. 1, 3 and 5), the teeth 22 (ie first engagementmeans) formed on the foot 20; a channel 38 formed in the fin box 16 andextending at least in part in a direction of the length of the fin box;and, a second engagement means in the form of a rack of teeth 40provided in the cavity 28.

The teeth 22 are engagable with the rack 40 in a plurality of differentpositions along a portion of the length of the cavity 28 when the pin 36is in the channel 38. The position of the fin 12 relative to the fin box16 can be varied or changed from one position to another by compressionof the resilient element 34 and sliding of the pin 36 along the channel38.

The various components and operation of the system 10 will now be lookedat in greater detail.

Referring in particular to FIGS. 3-5, the fin 12 is provided with a mainbody 42. The body 42 may be made of any desired known shape andconfiguration. Attached to the base 14 and extending in the plane of thebody 42 is the foot 20. However, in the case of a symmetrical fin (notshown), the foot 20 may lie in a plane slightly angled (eg 4° to 6°)from the plane of the fin body 42. The foot 20 includes a first part 44which depends from the base 14, and a second part 46 which extends fromone side of first part 44 parallel to and spaced from the base 14. Ahole 48 (see FIG. 4) is formed in the first part 44 for receiving theresilient element 34.

The lower surface 24 of the foot 20 is provided with a recessed portion50 which contains the teeth 22. Depending on the relative position ofthe fin 12 and the fin box 16, the recess 50 accommodates a section ofthe rack 40. A second transversely extending pin 52 is provided in thefoot 20 near the free end of the second part 46.

The resilient element 34 is in the form of a block of resilient materialsuch as rubber and is provided with a transversely extending hole 54through which the pin 36 passes. The element 34 is of a thicknesssimilar to the thickness of the foot 20 with the pin 36 having oppositeends extending from the hole 54.

As shown most clearly in FIG. 2, the fin box 16 is formed from twoelongate shell sections 56 and 58 which are coupled together. The shellsection 56 is depicted in FIGS. 6 and 7. The shell section 56 includes abottom wall 60, upwardly extending end walls 62 and 64, a side wall 66which extends between the bottom wall 60 and end wall 62,64; and, a topwall 68 extending laterally from an upper edge of the side wall 66. Thetop wall 68 in part forms the first surface 32.

A slot 70 is formed on the inside surface of the side wall 66 and formsone side of the channel 38. The slot 70 is provided with a first length72 running parallel to the bottom wall 60 and extending from above aboutthe second left most tooth on rack 40 to about half way along the lengthof the side wall 66. A second length 74 of the slot 70 runs parallel tobottom wall 60 and first length 72, and extends from a positionapproximately half way along the length of the side wall 66 terminatingclose to the end wall 62. A feed slot 76 extends upwardly connecting thefirst and second lengths 72,74 and opening onto the opening 30, top wall68 and first surface 32. That is, the lengths 72 and 74 are spaced oroffset from each other in a direction transverse to the length of thefin box 16.

A length of the top wall 68 extending from the end wall 62 to a positionroughly in line with the mid-point of the second length 74 is formedwith the same width as the end wall 62 and the bottom wall 60. Howeverthe remainder of the top wall 68 is reduced in width to the thickness ofthe side wall 66. When the shell sections 56 and 58 are coupledtogether, it is this reduction in the width of the top wall 68 whichdefines the opening 30.

Locating holes 78 a-78 d are formed at opposite ends of the end walls 62and 64, with a further locating slot 78 e formed in the side of the topwall 68.

Referring to FIGS. 8 and 9, the shell portion 58 of the fin box 16 is inthe form of a rectangular plate which, on an inside surface 80, isprovided with a slot 70′ configured as a mirror image of the slot 70described above and depicted in FIGS. 6 and 7. The slot 70′ includes afirst length 72′, second length 74′ and feed slot 76′. The surface oftop wall 68′ of the plate constituting the shell section 58 forms partof the first surface 32 when the shell sections 56 and 58 are combinedto form the fin box 16. Locating pins 82 a-82 d extend transversely ofthe surface 80 for registration with, and location in, locating holes 78a-78 d respectively. A transversely extending tab 82 e is also formed onthe surface 80 for registration with and location in the locating slot78 e.

The cavity 28 is defined by coupling the shells 56,58 together formingthe fin box 16. When this occurs, the slot lengths 72 and 72′; 74 and74′; and feed slots 76 and 76′ are facing each other to define thechannel 38. The facing lengths 72 and 72′ form a first portion 38 a ofthe channel 38, the facing lengths 74 and 74′ form a second portion 38 bof the channel 38 and facing feed slots 76 and 76′ form a feed channel38 c.

When in use, the fin box 16 is constructed by fixing the shell sections56 and 58 together, for example with glue or heat welding, and thendisposing the fin box into a recess formed in the hull of a water craftsuch as a surfboard. The fin box 16 is inserted into the recess withbottom wall 60 first, and disposed so that the surface 32 is coplanarwith the hull of the surfboard. The fin box may then be glued in placeby use of epoxy resins or other materials. To insert the fin, the pin 52is inserted into the feed channel 38 c constituted by the feed slots 76and 76′ to the bottom of that channel until it reaches the secondchannel portion 38 b. The pin 52 is then slid along the channel portion38 b toward end wall 62. As this occurs, the fin pivots downwardly aboutpin 52 until the pin 36 is aligned with the feed channel 38 c. Pin 36 isthen inserted into the feed channel 38 c to a position where it is inalignment with the first channel portion 38 a. This arrangement isdepicted in FIG. 1. In this configuration, the teeth 22 are spaced fromand not in engagement with the rack 40. With reference to FIG. 1, bysliding the fin 12 a short distance to the right the teeth 22 initiallyabut the rack 40. In order to effect engagement of the teeth 22 with thefin 40 the fin is now pivoted in an anti-clockwise direction about pin52. This causes compression of the resilient element 34 lifting theteeth 22 from the bottom wall 60. By now continuing to pull the fin 12toward the right, the teeth 22 can be disposed above selected teeth ofthe rack 40. When the desired location of the fin 12 has been reached,the compression on the resilient element 34 can be released which inturn biases the fin 12 to pivot in the clockwise direction about pin 52bringing the teeth 22 into engagement with the rack 40.

It would be appreciated that the position of the fin 12 relative to thefin box 16 can be manually varied for the length of the rack 40 bycompressing the resilient element 32 by rotating the fin anti-clockwiseabout the pin 52 and then sliding the fin left or right to a desiredlocation and subsequently releasing the pressure on the resilientelement 34. No tools are required to effect the change in position.Further, when the fin 12 is in either of its extremes positions, that iswith the right most tooth 22 engaging the left most tooth on rack 40;and the right most tooth 22 engaged between the last two teeth on theright hand side of the rack 40, the base of the fin 14 covers theopening 30 thereby substantially eliminating any drag, turbulence oradverse hydrodynamic effects otherwise caused by water flowing into theopening 30. It should also be appreciated that the forces that normallyact on the fin when in use tend to increase the force of engagementbetween the teeth 22 and the rack 40.

FIGS. 10-12 depict a fin 12′ for incorporation in a second embodiment ofthe adjustable fin system. In this embodiment, features which areidentical to those of the first embodiment are denoted by the samereference numbers while features which are similar in function butdifferent in structure are denoted with the same reference numbers butwith the addition of a ′ symbol.

In essence, the fin 12 depicted in FIGS. 10-12 differs from that of thefirst embodiment by forming the resilient element 34′ as a finger orspring which is coupled at one end to the foot 20 and extends into ahole 48′ formed in the foot 20 The pin 36 extends laterally fromopposite sides at the other end of the finger 34′. Ideally, the finger34′ and pin 36 would be formed integrally with the remainder of the fin12.

In this embodiment, the resilient biasing of the pin 36 is now providedby the resilience of the finger 34′. This resilience may be a functionsolely of the material from which the finger 34′/foot 20 is made oralternately in the event that the finger 34′ is formed separately of thefoot 20, by virtue of a resilient coupling or fixing of the finger 34′to the foot 20. The fin depicted in this embodiment functions in exactlythe same way as that depicted in FIGS. 1-9.

Now that an embodiment of the present invention has been described indetail it will be apparent to those skilled in the relevant arts thatnumerous modifications and variations may be made without departing fromthe basic inventive concepts. For example, the detent 18 is describedand depicted as including a rack 40 formed in the cavity 28 and teeth 22formed on the foot 20. However these may be reversed with the rack beingprovided on the foot and the teeth 22 formed in the cavity. In addition,the rack and teeth can be replaced by other inter-engagable elements,such as pins and holes for receiving the pins. Also, the resilientelement 34 is depicted as including a hole 54 for receiving the pin 36.However in a further variation, the element 34 may instead simply beprofiled so as to form with the hole 48 a passage for receiving the pin36. In another variation, the fin box may be manufactured in differentways than depicted, for example as upper and lower half shells, ratherthan side shells, or indeed as an assembly of more than two components.

All such modifications and variations together with others that would beobvious to a person of ordinary skill in the art are deemed to be withinthe scope of the present invention the nature of which is to bedetermined from the above description.

1. An adjustable fin system for a watercraft having a hull, said systemincluding at least: a fin having a base; a foot coupled to said base,said foot having a first portion extending from said base and a secondportion extending from said first portion, the second portion beingspaced apart from said base such that a fin box receiving area isdefined between the second portion of the foot and the base; a fin boxmountable in the hull of said watercraft, said fin box having a topwall, a bottom wall generally opposite the top wall, and side wallsintermediate the top and bottom walls, the walls defining a cavity forreceiving said foot, said cavity having an opening on a first surface ofthe top wall of said fin box through which said foot is inserted; and amanually operable detent mechanism for releasably holding said fin in aplurality of different positions relative to said fin box; wherein saidopening and said base are relatively dimensioned so that when said footis received in said cavity and when said fin is in any of the pluralityof different positions, said base substantially covers said opening andat least a portion of the top wall is positioned between the base andsecond portion of the foot within the fin box receiving area.
 2. Thesystem according to claim 1 wherein said detent mechanism includes afirst engagement means on said foot; and a second engagement means insaid fin box; said fast and second engagement means mutually beingengagable in a plurality of different positions along a length of saidcavity.
 3. The system according to claim 2 wherein said detent mechanismincludes a first pin resiliently supported on said foot and a channelformed in said fin box and extending at least in part, in a direction ofthe length of said fin box, and wherein said first and second engagementmeans arc mutually engaged when said first pin is in said channel, andthe position of the fin is changeable relative to the fin box byresilient deflection of said first pin relative to said foot and slidingof said first pin along said channel.
 4. The system according to claim 3wherein said detent mechanism includes a resilient element whichsupports said first pin, said resilient element supported by said foot.5. The system according to claim 4 wherein said resilient element is inthe form of a body of resilient material disposed in a recess formed insaid foot.
 6. The system according to claim 4 wherein said detentmechanism includes a finger coupled at one end to said foot.
 7. Thesystem according to claim 3 wherein said foot is provided with a secondtransversely extending pin, and wherein said second pin and said firstengagement means are respectively located near opposite ends of saidfoot and said first pin is intermediate of said second pin and saidfirst engagement means.
 8. The system according to claim 7 wherein saidchannel includes first and second portions for receiving said first andsecond pins respectively, and wherein said first and second portions arespaced from each other in a direction transverse to the length of saidfin box.
 9. The system according to claim 8 wherein said fin boxincludes a feed channel connecting said first and second portions andextending to said opening.
 10. The system according to claim 2 whereinone of said first and second engagement means is in the form of anelongated rack and the other of said first and second engagement meansis in the form of at least one tooth for engaging said rack.
 11. Thesystem according to claim 3 wherein one of said first and secondengagement means is in the form of an elongated rack and the other ofsaid first and second engagement means is in the form of at least onetooth for engaging said rack.
 12. The system according to claim 4wherein one of said first and second engagement means is in the form ofan elongated rack and the other of said first and second engagementmeans is in the form of at least one tooth for engaging said rack. 13.The system according to claim 5 wherein one of said first and secondengagement means is in the form of an elongated rack and the other ofsaid first and second engagement means is in the form of at least onetooth for engaging said rack.
 14. The system according to claim 6wherein one of said first and second engagement means is in the form ofan elongated rack and the other of said first and second engagementmeans is in the form of at least one tooth for engaging said rack. 15.The system according to claim 7 wherein one of said first and secondengagement means is in the form of an elongated rack and the other ofsaid first and second engagement means is in the form of at least onetooth for engaging said rack.
 16. The system according to claim 8wherein one of said first and second engagement means is in the form ofan elongated rack and the other of said first and second engagementmeans is in the form of at least one tooth for engaging said rack. 17.The system according to claim 9 wherein one of said first and secondengagement means is in the form of an elongated rack and the other ofsaid first and second engagement means is in the form of at least onetooth for engaging said rack.
 18. An adjustable fin system forwatercraft having a hull, comprising: a fin terminating at one end in afoot; a fin box mountable in the hull of said watercraft, the fin boxcomprising a cavity having an opening and sized to receive the foot ofthe fin, the cavity being larger than the foot in at least one dimensionto allow movement of the foot within the cavity; and a fin lock capableof being released by hand and operable to releasably lock the fin in adesired one of a plurality of positions relative to tide cavity; whereinthe fin comprises an overlapping portion extending about an entireperiphery of the fin adjacent the foot, the overlapping potion beingsized to extend beyond an entire periphery of the opening when the footis inserted in the cavity and the fin is in any one of the plurality ofpositions, the overlapping portion thereby restricting entry of waterthrough the opening.
 19. The adjustable fin system of claim 18 whereinthe fin lock is a detent mechanism having respective portions on wallsdefining the cavity and the foot.